Big block of 50+ halberds, 1-2 steam tanks, 1-2 great cannons, 1-2 units of Demi knights, 1 unit of 10+ inner circle knights, 1-2 small units of bows or crossbows, war alter, warrior priests, unkillable mounted
BSB, unkillable general, the giant spectrum thing that looks like a telescope on a cart, lv.4 wizard.........I don't play empire, but play competitively and go to a lot of tournaments and what I just stated seems to be a pretty common build for good empire armies. Obviously not everything i mentioned is taken at once, but most lists seem to come from this pool of units.
Case in point:
http://www.dakkadakka.com/dakkaforum/posts/list/552419.page